1. Background of the Invention
The present invention relates to a device for fixing, by means of elements exerting a pulling force, cross-pieces and/or cross members to pairs of vertical members and uprights in general, in particular to pairs of legs of chairs, small tables and the like.
2. Field of the Invention
In the art it is known that the fixing of cross-pieces to pairs of uprights forming the four legs of a chair, normally made of wood, is performed by forming, in the said legs, a seatxe2x80x94generally a circular hole or a quadrangular or polygonal recessxe2x80x94into which one end of the cross-piece is inserted, said end being suitably shaped so as to be correctly positioned inside the seat formed in the leg. Fixing of the ends of the cross-pieces inside said seats is performed, in certain cases, by means of engagement with slight forcing and, in other cases, by means of gluing.
It is also known that the systems which perform securing with glues or by means of simple engagement are, however, unable to ensure over time, in the case of prolonged use of the chair and owing to possible xe2x80x9cshrinkagexe2x80x9d of the wood, secure and permanent stability of the joint between legs and cross-pieces, so that the only solution to this problem is to perform disassembly of the chair and repair of the fitted or glued joint, even when only one cross-piece is loose.
Basically the present-day systems for securing cross-pieces to legs of chairs and tables in general do not allow rapid assembly and restoration of the stable joint between legs and cross-pieces, without having to perform time-consuming disassembly and subsequent reassembly operations which nevertheless result in alteration in the dimensions of the joint.
The technical problem which is posed, therefore, is that of providing a device for rapidly fixing cross-pieces to the legs of chairs, tables and similar structures, which is designed to overcome the drawbacks of the present fixing systems both of the type involving simple engagement and of the type using glues or other fixing means.
Within the scope of this problem a further requirement is to provide a device for fixing cross-pieces to uprights or vertical members of chairs, tables and the like, which is structured so as to allow both assembly and adjustment of the stability of the fixing joint of each individual cross-piece independently of the other cross-pieces and without the use of special tools.
A further object is to provide a fixing device of the type mentioned above, suitable for securing cross-pieces made of the various materials, such as wood, metal, rigid plastic or the like, to uprights or vertical members made of a material also different from that of the cross-pieces.
This technical problem is solved according to the present invention by a device for rapidly fixing cross-pieces to pairs of uprights, in particular pairs of legs of chairs, tables and the like, in which the cross-pieces have inserted within a pair of cylindrical elements which each have a first thread in opposite directions to each other for insertion, axially, into the opposite ends of said cross-piece and a second thread in the same direction as the respective first thread for insertion into a corresponding seat of said uprights, the rotation of the cross-piece in the same direction causing the simultaneous pulling of the two opposite uprights until they come into stable contact against the opposite ends of said cross-piece.
Further characteristic features and advantages of the present invention will emerge from the following detailed description provided with reference to the accompanying plate of drawings.